438 British Journal of Developmental Psychology (2018), 36, 438–451 © 2017 The British Psychological Society www.wileyonlinelibrary.com Strong and strategic conformity understanding by 3- and 5-year-old children Laurent Cordonier1,2*, Theresa Nettles2 and Philippe Rochat2 1Institute of Social Sciences, University of Lausanne, Switzerland 2Emory Infant and Child Lab, Department of Psychology, Emory University, Atlanta, Georgia, USA ‘Strong conformity’ corresponds to the public endorsement of majority opinions that are in blatant contradiction to one’s own correct perceptual judgements of the situation. We tested strong conformity inference by 3- and 5-year-old children using a third-person perspective paradigm. Results show that at neither age, children spontaneously expect that an ostracized third-party individual who wants to affiliate with the majority group will show strong conformity. However, when questioned as to what the ostracized individual should do to befriend others, from 5 years of age children explicitly demonstrate that they construe strong conformity as a strategic means of social affiliation. Additional data suggest that strong and strategic conformity understanding from an observer’s third-person perspective is linked to the passing of the language-mediated false belief theory of mind task, an index of children’s emerging ‘meta’ ability to construe the mental state of others. Statement of contribution What is already known on this subject? ‘Strong conformity’ corresponds to the public endorsement of majority opinions that are in blatant contradiction to one’s own correct perceptual judgements of the situation. Asch’s (1956, Psychological Monographs: General and Applied, 70, 1) classic demonstration of strong conformity with adults has been replicated with preschool children: 3- to 4-year-olds manifest signs of strong conformity by reversing about thirty to forty per cent of the time their correct perceptual judgements to fit with contradictory statements held unanimously by other individuals (Corriveau & Harris, 2010, Developmental Psychology, 46, 437; Corriveau et al., 2013, Journal of Cognition and Culture, 13, 367; Haun & Tomasello, 2011, Child Development, 82, 1759). As for adults, strong conformity does not obliterate children’s own private, accurate knowledge of the situation. It is in essence a public expression to fit the group and alleviate social dissonance. What does this study add? In three experiments, we explored the developmental emergence in the preschool years of strong conformity inference from a third-person perspective. Results show that by 5 years of age, and not earlier, children begin to construe strong conformity as a strategy that someone should use to gain social affiliation, even though they do not anticipate that a third-party individual would necessarily resort to such strategy. Additional data suggest that strong and strategic conformity understanding from an observer’s third-person perspective is linked to the passing of the language-mediated false belief theory of mind task. *Correspondence should be addressed to Laurent Cordonier, Institut des Sciences Sociales, Geopolis, Universite de Lausanne, CH-1015 Lausanne, Switzerland (email: [email protected]). DOI:10.1111/bjdp.12229 Preschoolers’ understanding of strong conformity 439 ‘Strong conformity’ is the process by which an individual publicly endorses a majority opinion to fit the group, even though this opinion contradicts his own correct perceptual judgement of the situation. Asch’s (1956) classic demonstration of strong conformity with adults has been replicated with preschoolers. In various testing situations, 3- to 4-year-olds manifest strong conformity by reversing about 30–40% of the time their correct perceptual judgements to fit with contradictory statements held unanimously by other individuals (Corriveau & Harris, 2010; Corriveau, Kim, Song, & Harris, 2013; Haun & Tomasello, 2011). These studies also demonstrate that, as for adults, strong conformity does not obliterate children’s own private, accurate knowledge of the situation. Strong conformity is, from the start, a public expression to fit the group. It is known that children tend to prefer ‘similar others’ (e.g., Aboud, 1988; Kinzler, Shutts, DeJesus, & Spelke, 2009). It is therefore likely that displaying similarity with others is early on a major mechanism of social affiliation. For example, 5- to 6-year-olds who are primed with ostracism engage in more precise imitations of others’ actions than children who are not (Over & Carpenter, 2009; Watson-Jones, Whitehouse, & Legare, 2016). Those primed with ostracism thus try to avoid social exclusion and gain social proximity by conveying similarity via imitation (see Cordonier & Deschenaux, 2014; Over & Carpenter, 2012, 2013). In the same vein, strong conformity could be a strategy to affiliate with others by communicating similarity. In the present research, using a third-person perspective paradigm, we explored whether and when preschoolers explicitly construe strong conformity as an affiliative strategy. Previous research confirms that by at least 9 years of age, children understand that a person with atypical appearance or behaviour should conform to majority standards to be socially accepted (Killen, Crystal, & Watanabe, 2002). Therefore, from at least that age, children explicitly construe group conformity as fostering social integration. Preschool- ers’ social-cognitive development suggests that we might find earlier signs of such explicit understanding of conformity as an affiliative strategy. By their second birthday, children develop a meta-representation of their own public image and start to actively manage it (Rochat, 2009, 2015). What remains unclear is when they understand that others, just like themselves, take care of their own public image – for instance, in displaying conformity with individuals they would like to befriend. Between 3 and 5 years, children develop the capacity to adopt and construe at an explicit level the perspective of others, as indexed by the passing of the false belief theory of mind (ToM) test (Callaghan et al., 2005; Wellman, 2002, 2013; Wimmer & Perner, 1983). From this point on, children start construing others on the basis of their mental states, including the third-party need to belong. We reasoned that these social-cognitive developments would allow preschoolers to construe and reflect explicitly about what other individuals should do to affiliate with a group. Our hypothesis was that children’s third-person perspective conformity under- standing would co-emerge with the development of a full-fledged ToM, as it depends on the construal of others’ perspective as developmental milestone. In the current research, we ran three experiments based on the same general procedure to document the early development of strong conformity understanding from a third-party perspective. Using three puppets depicted as friends, we asked 87 3- and 5- year-old children (tested individually) to anticipate the behaviour of a fourth, ostracized and otherwise identical puppet wanting to befriend the others. Following a treasure hunt script, all puppets discovered and looked into the same treasure box, announcing confidentially to the child distinct finds: object X for the three friends and object Y for the ostracized individual. The experimenter then asked the three friends to announce publicly what they saw in the box. After they declared that they saw object X, they turned 440 Laurent Cordonier et al. towards the fourth puppet asking what it saw in the box. At this point, the child had to guess what he or she thought the fourth puppet would say. In a follow-up question, the experimenter asked the child what he or she thought the fourth puppet should say to befriend the other three puppets (in Experiment 2, the order of questions was reversed). With the will test question, we probed whether the child spontaneously anticipated that the ostracized puppet would persist in declaring what it saw in the box, or whether it would change its answer by announcing to the group of friends that it saw the same object as they saw. With the should test question, we probed whether the child thought that the ostracized puppet would be better off displaying strong conformity to befriend the other three puppets. A response pattern consisting of a non-conformist answer to the will question (i.e., the child answering that the ostracized puppet would not conform its public claim to that of the three friends) along with a conformist answer to the should question (i.e., the child answering that the ostracized puppet should conform its public statement to that of the three friends) was interpreted as indexing a genuine strategic understanding of the affiliative potential of strong conformity. Our rational was that in this response pattern, expectation for conformity only occurs when the child is specifically prompted to imagine which might be the best strategy the ostracized puppet could use to fulfil its affiliative goal. Finally, using a simplified version of the classic false belief ToM task, each child in Experiments 1 and 3 was tested for his or her ability to represent others’ mental states. First established by Wimmer and Perner (1983), false belief ToM test has been widely used to assess the emergence of this competence between the age of 3 and 5 years (see Callaghan et al., 2005; Wellman, 2002). We hypothesized that success at this task would be positively correlated with the understanding of the affiliative